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Commit 45ba424f improved foreign key lookups during bulk updates when the FK value does not change. When restoring a schema dump from a database with many (say 100,000) foreign keys, this cache would grow very big and every ALTER TABLE command was causing an InvalidateConstraintCacheCallBack(), which uses a sequential hash table scan. This could cause a severe performance regression in restoring a schema dump (including during pg_upgrade). The patch uses a heuristic method of detecting when the hash table should be destroyed and recreated. InvalidateConstraintCacheCallBack() adds the current size of the hash table to a counter. When that sum reaches 1,000,000, the hash table is flushed. This fixes the regression without noticeable harm to the bulk update use case. Jan Wieck Backpatch to 9.3 where the performance regression was introduced.
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.